Jeremy Corbyn’s chief goal had been to remain as leader until the left had secured permanent control of the party. That meant staying on until the ‘McDonnell amendment’ had passed at conference and until the moderates in Labour HQ had been purged and replaced by Corbynistas. The imminent expected electoral wipeout puts this plan in peril – May’s decision is terrible for the left and the best news Blairites have had in ages.

There is “no chance” of an attempt by Labour moderates to remove Corbyn before the election. They need the left to own this defeat. That means six weeks of Blairites staying quiet about Corbyn and “talking about saving their local hospital”, being superficially loyal and trying not giving the Corbynistas an excuse to blame them for the outcome.

In 1983, after Michael Foot had led Labour to a huge defeat, a young Jon Lansman blamed the result on “the party machine” being “in the hands of the right”. Expect the Corbynistas to use the same excuse this time round – they need a ‘Blairite betrayal’ narrative to galvanise their grassroots if they are to stay in charge after June 8.

If Corbyn refuses to go when he loses, the party could well split. Moderates do not want to fight Corbyn in a third leadership contest. They hope he will stand down, departing before the left has succeeded in seizing the commanding heights of party structures. This means the moderates could lose dozens of MPs on June 8 but then win the next leadership election and regain control of the party. This election is a lifeline for the Blairites – they need to stay quiet for 51 days while they privately betray their party and hope Corbyn is annihilated at the ballot box…